Light-duty liquid (LDL) or gel detergent compositions useful for manual dishwashing are well known in the art. Such products are generally formulated to provide a number of widely diverse performance and aesthetics properties and characteristics. First and foremost, liquid or gel dishwashing products must be formulated with types and amounts of surfactants and other cleaning adjuvants that will provide acceptable solubilization and removal of food soils, especially greasy soils, from dishware being cleaned with, or in aqueous solutions formed from, such products.
Heavily soiled dishware can present special problems during manual dishwashing operations. Articles such as plates, utensils, pots, pans, crockery and the like may be heavily soiled in the sense that relatively large amounts of food soils and residues may still be found on the dishware at the time such soiled dishware is to be manually washed. Dishware may also be heavily soiled in the sense that food soil residues are especially tenaciously adhered or stuck to the surfaces of the dishware to be cleaned. This can result from the type of food soils present or from the nature of the dishware surfaces involved. Tenacious food soil residues may also result from the type of cooking operations to which the soiled dishware had been subjected.
When heavily soiled dishware is to be manually cleaned, very often highly concentrated, or high concentrations of, dishwashing detergent products are used. Frequently, this will involve direct application to the soiled dishware of a liquid or gel product in its undiluted or neat form. For such application, one detergent composition adjuvant which can be especially useful for solubilizing greasy food soils is a liquid hydrocarbon such as isoparaffin. Hydrocarbon materials, however, can be difficult to incorporate into aqueous detergent compositions without causing undesirable separation of the product into discernible oil and water phases.
One approach for incorporating hydrocarbons into aesthetically acceptable dishwashing detergent products involves the preparation of such products in the form of microemulsions. Preparation of stable microemulsions, however, requires selection of the right combination of surfactants, solvents, oil, liquid carrier components and other detergent composition adjuvants.
In addition to being suitable for cleaning dishware, LDL or gel compositions will also desirably possess other attributes that enhance the aesthetics or consumer perception of the effectiveness of the manual dishwashing operation. Thus, useful hand dishwashing liquids or gels should also employ materials that enhance the sudsing characteristics of the wash solutions formed from such products. Sudsing performance entails both the production of a suitable amount of suds in the wash water initially, as well as the formation of suds which last well into the dishwashing process. This typically requires incorporation of suds boosting surfactants which may also need to be incorporated into products in the form of microemulsions.
Given the foregoing, there is a continuing need to formulate manual dishwashing liquids and gels that provide an acceptable and desirable balance between cleaning performance, product form and product aesthetics. Accordingly, it is an object of the present invention to provide light-duty liquid or gel dishwashing compositions which are especially effective at removing greasy food soils from dirty dishware when such compositions are used in the context of a manual dishwashing operation.
It is a further object of this invention to provide such compositions in the form of microemulsions that can be used for manual dishwashing in either a direct application to dishware context or in an aqueous dishwashing solution context.
It is a further object of the present invention to realize such compositions that provide suitable and desirable sudsing performance.
It has been found that certain selected combinations of cleaning surfactants, suds boosters, liquid hydrocarbons, microemulsion-forming surfactants and other adjuvants can be made to provide dishwashing compositions that achieve the foregoing objectives. The elements of these selected combinations of ingredients are described as follows: